Modern jet fighters and other military aircraft are commonly equipped with a variety of weapons, including self-propelled missiles. Many such missiles are powered by air breathing, i.e., jet, engines. During storage and transport of such self-propelled missiles, it is desirable to cover the missile engine inlet so as to prevent foreign matter from entering the missile engine. As those skilled in the art will appreciate, foreign matter ingested into the engine may cause serious damage thereto when the engine is subsequently started, as discussed in further detail below.
In use, such missiles are commonly attached to the exterior underside, i.e., within the bomb bay or beneath a wing, of an aircraft by a missile launch rail, pylon, or bomb rack. As used herein, the term "launch rail" is defined to include all such means for attaching a missile to an aircraft and more particularly refers to that portion of an aircraft to which a missile is attached.
It is further undesirable to allow the missile engine inlet to be exposed to the onrush of airflow during flight of the aircraft, but prior to missile launch, since such exposure may potentially result in damage to turbine bearings or other internal structures of the missile engine. Additionally, it is desirable to prevent the ingestion of foreign material, e.g., stones, debris, birds, etc., by the missile engine during takeoff, flight, and landing of the aircraft, just as it is during storage, handling, and transportation of the missile. The ingestion of such objects frequently results in major damage to the turbines of such jet engines, and may even endanger ground personnel during testing, i.e., ground operation, of the missile engine. Thus, the undesirable ingestion of foreign objects not only affects the operational effectiveness of the missile, but also presents a serious safety hazard.
However, once the missile is launched, it is necessary to allow air into the missile engine inlet to operate the missile engine. Thus, it is necessary to remove any missile engine inlet cover prior to or during launching of the missile.
Various forms of missile engine inlet covers have been proposed. Such prior art missile engine inlet covers utilize electrical, mechanical, hydraulic, or pneumatic retraction systems for removing the missile engine inlet cover during missile launch. While generally effective to facilitate timely retraction or removal of the missile engine inlet cover, such elaborate systems undesirably contribute to the multiplicity and complexity of systems on board the aircraft and/or missile, thereby resulting in additional weight and space requirements, as well as increased maintenance. Further, such complex contemporary systems are susceptible to in-flight failure, including premature or late retraction or removal of the cover, frequently resulting in missile failure.
In view of the deficiencies found in the prior art, it is desirable to provide a reliable missile engine inlet cover ejection system which does not depend upon any other electrical, mechanical, hydraulic, or pneumatic device or system.